66844661400 has 576 divisors, whose sum is σ = 259759267200. Its totient is φ = 15668640000.

The previous prime is 66844661399. The next prime is 66844661423. The reversal of 66844661400 is 416644866.

66844661400 is a `hidden beast` number, since 6 + 68 + 446 + 6 + 140 + 0 = 666.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 57082815 + ... + 57083985.

It is an arithmetic number, because the mean of its divisors is an integer number (450970950).

Almost surely, 2^66844661400 is an apocalyptic number.

66844661400 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66844661400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (129879633600).

66844661400 is an abundant number, since it is smaller than the sum of its proper divisors (192914605800).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66844661400 is a wasteful number, since it uses less digits than its factorization.

66844661400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1269 (or 1223 counting only the distinct ones).

The product of its (nonzero) digits is 663552, while the sum is 45.

It can be divided in two parts, 6684466 and 1400, that added together give a palindrome (6685866).

The spelling of 66844661400 in words is "sixty-six billion, eight hundred forty-four million, six hundred sixty-one thousand, four hundred".